The present invention relates to the field of fire retardant or fireproof products, particularly sheet or board shaped products, based on fibrous organic or inorganic materials.
The ever increasing demands for fire protection for materials of all types make it necessary to make all fibrous materials, even organic materials, fireproof or fire resistant, or to prepare them in such a way that they do not contribute to the initiation or continuation and support of a fire. The manufacture of materials of organic fiber substances however, is only possible in an economical manner if a wet process is used, i.e. in very dilute aqueous suspensions. However, the use of such dilute suspensions is not a satisfactory method for the introduction of fire protection agents which are soluble in water or could be washed away with the waste water.
German Patent Application No. P 28 31 616.7 which corresponds to U.S. Patent Application Ser. No. 057,266, discloses a method for producing a noncombustible material made of mineral substances in which residual waste water clarification sludges and/or moist wood chips are used to form a solid body. In this process, boron minerals are added to the basic structural materials and these boron minerals are mixed with sulfuric acid. The resulting mixture is then bonded together with a synthetic resin and hot pressed. The material produced in this way has properties similar to wood chip board, but, due to the proportion of boric acid as well as some glass or ceramic forming minerals which it contains, it is non-combustible. This known material is also similar to wood chip board in its manner of manufacture which, except for the incorporation of the fire protection agent, is identical to the manufacture of wood chip board. The starting materials should therefore be practically dry or have a moisture content of at most 25%.